ECG Basic Principles

Question 1

What is a electrocardiogram?

Answer 1

A graphic Representation of depolarization and repolarization in the myocardium

Question 2

Where does the first depolarization take place?

Answer 2

Top left heart??? Not at the apex

Question 3

Where does the Sinus node depolarization take place?

Answer 3

Right before the PR interval

Question 4

Why are the repolarization and depolarization both positive?

Answer 4

They occur in opposite directions. and have opposite charges which cancel out.

Question 5

How was the direction of cardiac impulses discovered?

Answer 5

Vector cardiography

Question 6

What phase does the ST segment correspond to?

Answer 6

Phase 2

Question 7

Where do the lines of einhoven’s triangle intersect?

Answer 7

the AV junction

Question 8

What is different about the Transverse (V) leads?

Answer 8

There is no resistance in the leads

Question 9

What are the methods of determining HR?

Answer 9

Count complexes in 6 sec or

Memorize the rates for each large square

Question 10

What are the rates for each large square?

Answer 10

300
150
100
75
60
50
43
37
35
30

Question 11

What are the Variables in ECG interpretation?

Answer 11

Duration
Amplitude
Morphology
Vector

Question 12

What are the qualities of the P wave?

Answer 12

Record both atrial depolarizations
Upright in inferior and lateral leads
ALWAYS Negative in aVR
Duration

Question 13

What are instances that would have a Positive P wave in aVR?

Answer 13

Incorrect lead placement

AV node is the pacemaker

Question 14

What could prolong the P wave?

Answer 14

Larger atria making signal take longer to travel

Question 15

Which lead is the best for looking at the P wave?

Answer 15

Lead 2

Question 16

Anatomically, where is the Right/ Left atrium?

Answer 16

Anterior/Posterior

Question 17

Where is V1 in relation to the RA?

Answer 17

It is placed directly over the RA

Question 18

What will you see in a prolonged P wave in Lead 2?

Answer 18

A notch in the P wave

Question 19

What can increse the P wave amplitude?

Answer 19

Larger mass of Atria

Question 20

What does the PR interval tell you?

Answer 20

Depolarization events from atrium through AVN, his bundle, bundle branches, and purkinjie fibers

Question 21

What is the normal duration of PR interval? 1st degree AV block?

Answer 21

.12-.20sec
PR >.20 sec
Increases with age

Question 22

What is a short PR interval called?

Answer 22

Pre-excitation

Question 23

What is the normal duration of QRS interval?

Answer 23

.07-.11 sec

Question 24

What does increased amplitude of QRS tell you?

Decreased?

Answer 24

Tall or deep tells you increased muscle mass or chamber dilation

Low Voltage

Question 25

What is the Q wave?

Answer 25

First downward deflection from baseline

Question 26

When will a Q wave be visible?

Answer 26

After an MI there will not be the same cardiac activity to overshadow it.

Question 27

Normal length of Q wave?

Question 28

What is the R wave?

Answer 28

The first upward deflection from baseline | High left septum depolarizing toward V1

Question 29

What happens to R wave as you go from V1-V6?

Answer 29

It increases in amplitude

Question 30

What Is the Second R wave in the same complex called

Answer 30

R prime

Question 31

What is the S wave?

Answer 31

First downward deflection from baseline after initil R wave

Question 32

What happens to the Sa wave as you go from V1-V6?

Answer 32

It decreases in amplitude

Question 33

What is the name of the point where the ST segment and the T wave come together?

Answer 33

The J point

Question 34

What does an elevated or depressed J wave tell you?

Answer 34

Repolarization abnormality

Question 35

What does the T wave tell you?

Answer 35

Ventricular Repolarization

Question 36

What is the normal amplitude of T waves?

Question 37

What direction does the T wave usually go?

Answer 37

In the same direction as QRS

Question 38

What is a U wave?

Answer 38

Small, rounded wave after T.

Question 39

What does the QT interval measure?

Answer 39

Measures duration of activation and repolarization or entire ventricular myocardium Beg of QRS to end of T wave

Question 40

What is the normal rane of axis in normal people?

Answer 40

-15 to 100 degrees

Question 41

What is the Axis?

Answer 41

Mean direction of ventricular myocardiumdepolarization

Question 42

What is the axis if 1 is positive and aVF is positive?

Answer 42

Normal

Question 43

What is the axis if 1 is negative and aVF is negative?

Answer 43

Leftward

Question 44

What is the axis if 1 is negative and aVF is positive?

Answer 44

rightward